Method for forming highly reactive olefin functional polymers

Abstract

A process for the preparation of polybutene having an exo-olefin content of at least 50 mol. % from an isobutene-containing monomer feedstock, which process comprises contacting said isobutene-containing feedstock with a Lewis acid catalyst complexed with a Lewis base, in an apolar polymerization medium, and initiating polymerization of said isobutene-containing feedstock. The Lewis acid catalyst is of formula R′AlCl2, wherein R′ is hydrocarbyl; the Lewis base is a dihydrocarbyl ether wherein each hydrocarbyl group is independently selected from C1-C8 hydrocarbyl groups and one or both hydrocarbyl groups of the dihydrocarbyl ether are substituted with an electron-withdrawing group; and the initiator is a compound of formula RX, wherein X is a halide; R is a hydrocarbyl group capable of forming a stable carbocation, and the carbon linking group R to group X is tertiary, benzylic, or allylic.

What is claimed is: 
     
       1. A process for the preparation of polybutene having an exo-olefin content of at least 50 mol. % from an isobutene or an isobutene-containing monomer feedstock, which process comprises contacting said isobutene or isobutene-containing feedstock, with a Lewis acid catalyst complexed with a Lewis base, in a substantially or completely apolar polymerization medium, and initiating polymerization of said isobutene or isobutene-containing feedstock with an initiator, wherein said Lewis acid catalyst is a Lewis acid of the formula R′AlCl 2 , wherein R′ is a hydrocarbyl group; said Lewis base is a dihydrocarbyl ether wherein each hydrocarbyl group is independently selected from hydrocarbyl groups having 1 to 8 carbon atoms and one or both hydrocarbyl groups of the dihydrocarbyl ether are substituted with an electron withdrawing group and the initiator is a compound of the formula RX, wherein X is a halide; R is a hydrocarbyl group capable of forming a stable carbocation, and the carbon linking group R to group X is tertiary, benzylic or allylic; wherein the catalyst complex is pre-activated by addition of water, and the pre-activated catalyst complex is subsequently reacted with from about 0.1 to about 2 molar equivalents, per equivalent of Lewis acid, of a trialkyl aluminum compound wherein each alkyl group of said trialkyl aluminum compound has at least 2 carbon atoms. 
     
     
       2. The process of  claim 1 , wherein R′ is an alkyl group having 1 to 12 carbons. 
     
     
       3. The process of  claim 1 , wherein said Lewis base is dihydrocarbyl ether wherein each hydrocarbyl group is independently selected from hydrocarbyl groups having 1 to 8 carbon atoms and one or both hydrocarbyl groups of the dihydrocarbyl ether are substituted with a chlorine atom. 
     
     
       4. The process of  claim 3 , wherein said Lewis base is a dihydrocarbyl ether wherein each hydrocarbyl group is independently selected from alkyl groups having 1 to 4 carbon atoms and one or both hydrocarbyl groups of the dihydrocarbyl ether are substituted with a chlorine atom. 
     
     
       5. The process of  claim 1 , wherein the Lewis acid and Lewis base are complexed in a solvent selected from the group consisting of mixed C 4  to C 12  linear and/or branched hydrocarbons, toluene, and xylene. 
     
     
       6. The process of  claim 1 , wherein said apolar polymerization medium is selected from saturated C 4  hydrocarbons, unsaturated C 4  hydrocarbons, and mixtures thereof. 
     
     
       7. The process of  claim 1 , wherein said isobutene or isobutene-containing feedstock is selected from pure isobutene; a C 4  refinery cut containing between about 20-50% isobutene, between 5% and about 50% butene-1, between about 2% and about 40% butene-2, between about 2% and about 60% iso-butane, between about 2% and about 20% n-butane, and up to about 0.5% butadiene, wherein all percentages are by mass, based on the total mass of the C 4  refinery cut; and mixtures of pure isobutene and said C 4  refinery cut. 
     
     
       8. The process of  claim 1 , wherein said catalyst complex is pre-activated by addition of from about 0.02 to about 10 equivalents, per equivalent of Lewis acid, of water. 
     
     
       9. The process of  claim 1 , wherein said Lewis acid catalyst complexed with a Lewis base, is contacted with said isobutene or isobutene-containing feedstock at a concentration of millimoles of Lewis acid-Lewis base complex per liter of feedstock of from about 0.2 mM to about 200 mM. 
     
     
       10. The process of  claim 1 , wherein the polymerization process is conducted continuously. 
     
     
       11. The process of  claim 1 , wherein said polybutene product has an exo-olefin content of at least 70 mol. %. 
     
     
       12. The process of  claim 1 , wherein said polybutene has a number average molecular weight (M n ) of from about 400 Daltons to about 4000 Daltons. 
     
     
       13. The process of  claim 1 , wherein said trialkyl aluminum compound is selected from the group consisting of trioctyl aluminum, triisobutyl aluminum, triethyl aluminum, and mixtures thereof.